Cutting a Map File: Layers, Kerf, Cut Order and Fixes

A layered map is not one file. It is one file per physical sheet, all drawn at the finished size and sharing the same outer shape so they stack. Inside each file, every line is tagged by what the laser should do to it.

• The outline. The outer shape of the piece. Always a cut, always closed.
• Cut lines. Closed paths that go all the way through: water edges, street strips, inner holes.
• Score lines. Light vector lines on the surface, used for minor streets, contours and guides.
• Engrave areas. Filled shapes burned into the surface: streets, text, art.
• Optional marks. Registration marks for print-and-cut, or glue guides showing where the next sheet sits.

The rule from one laser maker's island map guide holds for every map: vector only, closed paths for cuts, and one layer per material thickness.

Laser software splits a file into operations by stroke color. Pick a scheme and never change it, so a file from last year still imports right.

In LightBurn, MappSmith puts score on its own engrave-type layer rather than the cut layer, so you can give it its own power and speed. The settings stored in the file are placeholders. Replace them with your own tested numbers. In the Glowforge app, the three colors come in as three separate steps.

Kerf is the width of material the beam removes. A cut road strip loses kerf from both edges, so a road drawn at the width of your kerf can vanish completely. Features smaller than the kerf are lost.

• The range. Kerf runs from about .008" to .040" (roughly 0.2 to 1 mm) depending on process and material.
• Measure yours. Cut a 1" square and measure it. A result of 0.990" means a beam width of about 0.010".
• Settings change it. Slower speed or higher power widens the kerf, so measure at the settings you will actually use.

In MappSmith each road group and line feature has a line width from 0.05 mm to 3 mm. Engraved and scored lines can go thin. Cut streets need enough width to survive, and very thin cut lines snap.

The other side of kerf is tiny pieces. A map is full of them: little islands, pond outlines, slivers between two roads, on-ramps. Each one is a part that falls through the bed or burns away.

• Drop what will not survive. One island map guide puts it simply: "avoid extreme detail that will burn away."
• Smooth before you cut. A tracing tutorial smoothed the result to "eliminate tiny cuts like these onramps."
• Zoom to real size. View the file at 100% on screen. If a feature is hard to see there, it will be hard to cut.
• Use a smallest-piece filter where you have one. MappSmith's Terrain & Depth panel has a Smallest piece setting from 0 to 15 mm that leaves out pieces and holes below that size and tells you how much ground that is at your scale.

A floating piece is any cut shape that touches nothing once it is free. On a street layer, that means a road that ends in mid-air, or an edge road that the crop cut off from the network.

1. 01Add a frame bandA solid ring or border around the piece gives every road end something to join. Union the roads into it so they become one shape.
2. 02Keep road groups togetherMap data changes a road's type along its length, for example where a highway becomes a ramp. If you cut one type and drop the next, the road ends in mid-air. Cut related types together.
3. 03Bridge what is leftFor a stubborn island, draw a short strip to the nearest road or to the band, and union it in.
4. 04Check before you cutLook at the street layer alone and ask of every strip: what holds this?

MappSmith does this check for you. Pieces-only layers are welded into one connected cut in the download, the welded preview shows exactly that, and the layer warns you if a piece is attached to nothing. If one still is, the download stops rather than give you a file that cuts into loose parts.

Once a piece is cut free, it can drop or shift a hair. Anything cut after that lands in the wrong place. So the order is always:

1. Engrave (the sheet is still whole and flat).
2. Score.
3. Inner cuts: road gaps, water edges, holes.
4. The outer outline last.

Most laser software can order cuts inside-first automatically. Turn it on and check the preview once. If your machine does not, put the outline on its own layer and run it last.

One maker who switched found scoring was faster and made the roads stand out more. A common pairing from laser makers' own map tutorials is to cut the water and engrave the roads. Try both on a scrap of your crop and pick the one you like from across the room, not from six inches away.

Ornaments, coasters and small gifts make money in batches. A 3.25" pitch nests about 18 round ornaments on a 12x20 sheet (our math: 3 across by 6 down).

• One material per sheet. Nest only layers cut from the same stock.
• Leave a margin and spacing. Pieces too close share a kerf and weaken.
• Group by operation. Run all engraving, then all scoring, then all inner cuts, then all outlines.

In MappSmith, Sheets lays several saved maps out on one piece of stock. Pick the stock size, margin and spacing, and it lists anything too big or unplaced in amber rather than dropping it. Sheets come with the plan or the free trial.

If one map is bigger than your bed, split it. One maker intersected a large map with rectangles in Inkscape and added snap marks to rejoin the tiles. MappSmith's map tiles product splits a map across boards that hang side by side, each with its own frame band.

1. 01Material test gridFind cut, score and engrave settings on the exact sheet you will use. Plywood varies from pack to pack.
2. 02Kerf squareCut a 1" square, measure it, and write the kerf on the sheet edge.
3. 03Narrowest road testCut a small corner of the street layer with its thinnest road. If it snaps or burns away, widen that road group.
4. 04Full dry run on cardboardRun the whole map on chipboard or cardboard. Stack the layers and check alignment before you spend wood.

For the bigger picture, start with how to make a laser cut map.